Navigation instrument



NOV. 26, 1946. A MacKAY NAVIGATION INSTRUMENT 5 Sheets-Sheet 1 Filed June 24, 1944 N0v.26,1946. A MMKAY" 2,411,690

' NAVIGATION INSTRUMENT Filed June 24, 1944 'Sheets-Sheet. 2

HIFI'. UF LATITUDE lllllllll IHIIHII HH DEFA TUR llll llll llllIllllElllllllll llllllll ',0 DEFA TUR disposed with respect to the lower half of the circular degree scale I2 so that either half of the latter may be employed in angularly positioning the scales I, 2 and 5 as presently to be described. Scales I, 2 and 5 are made, respectively, with apertures 2l, 22 and 23 (Figs. 5, 6 and 10) to receive post C,

A scale t is also provided which is formed near one end withk an aperture 24fso that it can-be mounted upon bolt D as shown in Figs. 1 and 3 with capacity for angular adjustment thereon, and so that it is bodily adjustable toward and from post C with scale 3. This scale 6 is also graduated in units representing nautical miles as measured from the axis of bolt D.

4 tained in their adjusted positions until scale 3 does measure and indicate the proper distance between said two points of intersection. Thus the requirement for adjustment of scale 3 as just described shows that the vessel has been set to starboard by current or Wind and the extent of this deflection is shown on scale 4 at the point Where it is intersected by scale 3. Also, the distance between the point of intersection-of scale 2 with scale 3 and the pivot post C, asimeasured o n scale 2, is the distance of the vessel from the landmark.

If, after angularly adjusting or setting scale 2 All of the above described scales are preerably r made from transparent sheet material such as Lucite, Vinylitej or the like.

By means of the above described instrument .the navigator of a coastwise vessel that is in sight of a Axed landmark whose position is shown upon hischart may Iplot a chosen or predetermined course past said landmark and may Afrom time to time locate his vessels position on the chart, its position with respect to said predetermined run or course, and its distance from said landmark, so long as the latter is visible from said vessel, said instlument at the same time providing for determination of the set, drift and course made good over the ground after each logged run.

and also shown upon the navigators chart, such as a lighthouse, and that the tc-p edge of scale 3 is to represent the proposedA or chosen course or run that is to be made past the same, a careful compass bearing is taken of the actual landmark and by means of this bearing and compass scale l2 the radial scale i is set at a corresponding angle, relatively to course scale 3. 'I'hen scale 3 is adjusted into a position where it intersects scale I at a point on the latter corresponding with the known distance of the vessel from the landmark represented by pivot post C. Scale 3 will then intersect scale 4 at a distance from pivot post C, as measured on scale 4, at which the vessel will pass abeam of the landmark. At this time a note is made of the reading of the patent log.

After the vessel has proceeded a convenient distance a second bearing is taken on the actual landmark and a second reading of the patent log is made and noted, whereupon radial scale-2 is angularly adjusted on compass scale l2 to agree with this second bearing and .the point of intersection o-f scales 2 rand 3 will indicate the position the vessel should occupy if it had remained upon the predetermined course represented by scale 3 while traveling from the position indicated by scale I to the position indicated by scale 2. At .the same time the' distance between scales I and 2, as measured byscale 3, will show the distance traveled over the ground provided the vessel had not deviated from the proposed course in which case this distance should be the same as the difference between the rst and second log readings.

.If, after angularly adjusting or setting scale 2 in accordance with the second compass bear- `the irst and second log-readings, then the course scale 3'is adjusted inr a direction away from pivot post C While scales I and 2 are rethe distance between the points of intersection of scales I and 2 with scale 3, as measured by the latter, is more than the difference between the liirst and second log-readings, then the course scale 3 is adjusted in a direction toward pivot C until scale 3 does indicate the proper distance between said two pointsv of intersection, thus showing that the vessel has been set to port by current or wind and the extent of this deection is measured on scale 4. Also, after thus adjusting the instrument thedistance between the point of intersection of scale 2 with scale 3 and the pivot post C, as measured on scale 2, is the distance of the vessel from the landmark.

Due allowance having been made for set and drift of current and scale lI having been adjusted to occupy theposition of scale 2, the vessel 'proceeds upon its course for a second convenient distance at the end of which the operations above described including adjustmentiof scales 2 and`3 are repeated. Thus the vessel is piloted step. by step on the predetermined course until all of scale 3 has been utilized, whereupon a second landmark ahead is selected and a second course fiixed upon.

The scale 4 is also adapted to beused with scales 5 and 6 to compute set, drift and course made good over the ground. This is accomplished as'follows:

` Assuming that the vessel moves from C toward D a distance of say 15 knots as shown by the patent log, during a given period of time, say one hour, then -at the end of that period of time scale 3 is adjusted along scale 4 into a.` position where bolt D registers with I5 on scale 4. Scale 6 is then set atan angle with respect tol scale 4 where it is parallel with the direction of the current at the point corresponding with the positionof D as shown by the navigators chart or :given on the navigators table of currents.` The position relativelyto C and D the actual course of the v`vessel made Vgood overthe ground and `also the speed-made good over the ground in knots per hour, the latter .being shown by the graduations of'scale 5. i I Y The relative positicnsof the scales 4, 5 and 6 vshown in Fig. 1 ofthe4 drawings, although `exaggerated, may be used to explain this lfurther.;v vrAs shown in this figure the pivot D registers with scale 4 at a point indicating a travel of 15 miles during the selected period of time .of -one hour; the angle at lwhich scale 6r is setl with respect n to scale 4 indicates the langular relationship ber tween the .direction of ,the currentrwith respect to the proposed course C-D, while scale 5 is emigeeo knetsas measured 4cn scale 'the latter,."b'eingfjshovvn 1by Y which `ilfuld otherwise operate to tithe `vessel"from its proper' Vstraight line will be'V directed by eer a Acou'rseat an I(Fig. D equal to ,d`1 f 'co rse"'from C 'toD 'the :pilot ithe adjusted instrument to' .angleandfto 'the fleft of sfcal tHe-angle '4-5' with resulttnat the 'vessel will 2 t vieljanapproximately',straight line Ycourse 'from ..lrtthe cnartinsicate vthe *current as parallel with scale '3.,' tnen'lit 'is netnecessary itc utilize 6 v'loiltfscale `3V can 'be'sd tol'me'a'sure `the rtsi the current by adjustment of scale fg, oi'the speed, of A1n' nautical lnl'e'son 's starting frein' pivot D, and placing .scale tnelatter at that point. minary to gthe'prcper l rom pivot C ,the scale the scale t c'rgf the current n orgparallel'with the "scale y I, f witnoutusecf scale .s g. ,A The use 6r scales t, 5 and t's-thusindependent ,'Qfithe use'f scales l1, 2,"3 and `li., exceptftlia't from fthe 'fact s as 'deteri'rinediby '4,5 Yandjlijtlfleproper "setting y o tVA wit respect to point Cisiaceompl'ished.- ,"S'al'es r4, "5 and `6 areeinployed'to deterfthe .euectiye current influence to vwhich the f be .subjectedin "traveling 'over a proposed4 coursel'and from this information `can nbe,determi-r1edI the proper, steering course on 44whicnjto'proceed`intraveling.frompointC. Y f "Asistated above, eachscale 1,2 Iand 5 Vis graduatedjthe same ln itslljp'csite sides and 'thebnly the ttvseries .or 'graduaticns editieren betw en ...vini lthosefuponone hose upon' opposite sideV thereof, value whieh'tiie iuseridf, the instrumen ay elec Ito allot t'o Aeach Juni't,` I-Iowever,"'inV Fig. 'l yfoijtlie drawings one side'oi eachofthe three scale` referredtc isffuppermost and its gradual-Lions' may, as shown, benumbered to x the value of each unit thereof as one mile, while in Fig. 4 of the drawings the opposite side of each unit thereof may be regarded as 5 miles. The lower value of one mile per unit, when fixed mentally or by numbers, renders the instrument particularly adapted for coastwise sailing where length cf the .ccursemade goed :over

n Icrue 'to :compensate fori-.lie c l lowing on scale 5. kWith thissetting of the scales -3 and '5" the distance between bolt D and scale f5,- `as measuredon scale 3, is equal tov the departure, and at the ksame A:time the'dista'nce between pivot VpostC andl the difference in'latitude. n l when, 4during f middle latitude sailing; the "diierence of latitude and the departure are vlanown, the instrument may be used to determine the course and distance as follows: The known information includes the jdiiferencebf latitude which, for example, Vmay be 136 miles, vand the departure may be' assumed to be 203 miles, LWeste'rly.v Scale 3 is now, registered with 136-miles on scale 4 and .scale .I is registered withpa pointfon .Scale f3 that iridicalj/es 203 miles to ltlie'ljeft'of pivot post D. "Scale 'I now lregisterswith compass scale I'Llto' show :a ,compass course of '56 degrees west- .a'nd the' distance from pivot 'post 4|C` tojthe 'point Yof intersection between scales '3 and l 'gives the vcourse distance as 2744.3 miles. rc'rnft'ne twoijexamples given in the immedie'ding'tWo paragra" hs it should v'be 'clear trument above describedmayalso be employed.. 11i l'Xleditiou sly. determining the fol- (lllhei departure` anddistance :when the vcompass cburse anddiffefren'ce of vlatitude are y 25 'The Icistance anuuifierence of vllati. 1 frienlthe course and departureare known. (Elv The course and dpartur when the `'distance 4vandeinenergie ci latitude are knnwmand (i4 the vcourse' and dinerence of latitude when the *disjtan'ce and departure `"are known. 'U j VTo determine difference of longitude the Jprocedu're .is as follows: `'The departure is 'first dene "instrument :as above this departure is ,ue-scribed, or otherwise, 'and each of the three i scales referred to isuppermost and the value of Y is then reajd l,scale '4 corresponding with the'fn'iddle'flatitllde course. i., Tne ,digerente Lof 'longitu series of compass graduations; two straight elonthe runs are relatively short, while the higher value oi 5 miles per unit, when xed mentally or by numbering, renders the instrument particularly adapted for middle latitude sailing where the courses are relatively much longen If the value of each unit of scales I, 2 and 5 is iixed mentally then the numbering may be omitted and the instrument used for both coastwise and middle latitude saling with said scales permanently arranged on pivot post C as shown in Fig. 1, but when numbered as shown in the drawings said scales are reversed uponpost C as shown in Fig. 4 while middle latitude sailing.

When,-during middle latitude sailing, the com-v gate scale members extending diametrically across said circular series of compass graduations and pivotally mounted intermediatetheir ends upon said panel for angular adjustment on anvaxis at y' the center of said circular series of compass graduations and each bearing a longitudinal series of mileage graduations disposed so as to be read as starting at said axis; a third transversely disposed straight scale member bearing a longitudinal series of mileage graduations; a xed scale of mileage graduations on said panel extending radially away from said axis perpendicularly toward said transversely disposed scale member and disposed' so as to be read as starting at said axis, the mileage graduations of said third transversely disposed scale member being disposed so as to be read in either direction from the point of intersection of said third' member with said fixed rav'dialscale, and means slidably connecting said third transversely disposed scale member to said base panel so that it is manually adjustable bodily on said panel toward and from said axis while held against, endwise and pivotal displacement and with its intermediate portion intersecting said two first-mentioned scale members and also said lfixed radial scale; a fourth straight elongate scale member extending diametrically across said circular series of compass graduations and pivotally mounted intermediate its ends upon said panel nfor vangular adjustment on said axis, said fourth member bearing a longitudinal series of mileage graduations disposed so as to be read as starting at said axis, and a fth current-direction indicating scale member co-operatively associated with said fourth scale member, said fth member being .pivotallyi connected with said third transversely y disposed scale member at the point of intersection of the`latter with said radial scale and bearing a longitudinal series of mileage graduations disposed so as to be read as starting at said point of intersection.'

lcomprising a base panel bearing a fixed circular series of compass graduations; an elongate scale ymember extending diametrically across said circular series of compass graduations and pivotally Amounted upon said panel for angular adjustment on an axis at the center of said circular series of compass graduations, said member bearing mileage graduations disposed so as to be read as starting at said axis; a second transversely disposed straight scale member bearing mileage graduations and co-operable with said first scale member to determine the course made good over the ground; a fixed scale of mileage graduations on said panel extending radially away from said axis perpendicularly toward and across said second transversely disposed scale member; means connecting said second transversely disposed scale member with said panel so that it is slidably adjustable bodily on saidpanel toward and from said axis while maintained in position al; right angles to said xed radial scale; and a third current-direction indicating scale member co-operatively associated with said frst'scale member, said third member being pivotally connected with said second transversely disposed scale member at the point of intersection of the latter with said radial scale and bearing a longitudinal series of mileage graduations disposed so as to be read as'starting at said point of intersection.

5. An instrument of the character described comprising va base panel bearing a ixed circular vseries of compass graduations; two straight elongate scale members extending diametrically across said circular series of compass graduations pivotally mounted intermediate their ends upon said panel for angular adjustment'on an axis at the center` of said circular` series ofr compass graduations and each bearing a longitudinal series of mileage graduations disposed so as to be read as starting at said axis; a third transversely disposed straight scale member co-operatively disposed with respect to said two members and bearing a longitudinal series of mileage graduations; a xed scale of mileage graduations on said panel extending radially away from said axis perpendicularly across said third transversely disposed scale member and disposed so as to be read as starting at said axis; means connecting said third transversely disposed scale member with said panel so that it is'slidably adjustable bodily on said panel toward and from said axis while maintainedin a position at right angles to said xed radial scale, and a fourth straight elongate distance-indicating scale member co-operatively associated with said third transversely disposed, scale member and said compass graduations, said fourth member Vbeing pivotallyvmounted upon said panel for angular adjustment on said axis and bearing a longitudinal series of mileage graduations disposed so as to be read as starting at said axis, and

'- said third transversely disposed scale member bearing mileage graduations to be read in either direction starting at the point of intersection of said fixed radial scale with said third transversely disposed scale member.

1 ANGUS MACKAY. 

